The open-loop transfer function of a feedback control system is G(s)=$${1 \over {{{\left( {s + 1} \right)}^3}}}$$
The gain margin of the system is

The characteristic equation of a feedback control system is given by
s³ +5s² +(K + 6)s + K =0
Where K > 0 is a scalar variable parameter. In the root loci diagram of the system the asymptotes of the root locus for large values of K meet at a point in the s-plane whose coordinates are

A second order system has a transfer function given by $$\mathrm G\left(\mathrm s\right)\;=\;\frac{25}{\mathrm s^2\;+\;8\mathrm s\;+\;25}$$ .If the system, initially at rest is subjected to a unit step input at t = 0, the second peak in response will occur at

In the signal flow graph of Figure, the gain c/r will be